This GIMP tutorial teaches how to remove backgrounds using the Lasso Tool in 3 steps: 1. Import the image layer and ensure it has an alpha channel for transparency. Scale the image to the desired size. 2. Use the Free Select Tool or Pen Tool to trace around the subject, selecting the background area. 3. Hit delete to remove the selected background, leaving only the transparent subject. The process can then be repeated for any other sides to fully isolate the subject from its original background.